#include <algorithm>
#include <iostream>
#include <iomanip>
#include <sstream>
#include <string>
#include <list>
#include <bitset>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cctype>
#include <cmath>
#include <cassert>
#include <ctime>
#include <numeric>
#include <functional>
#include <valarray>
#include <complex>
#include <utility>
using namespace std;

const int dx[]={0,-1,0,1,-1,1, 1,-1};
const int dy[]={1,0,-1,0, 1,1,-1,-1};
const double eps=1e-8;

typedef long long LL;
typedef unsigned long long uLL;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<vi> vgraph;
typedef vector<pii> vpii;
typedef vector<LL> vLL;
typedef vector<string> vs;

#define sz(a) (int)a.size()
#define fori(i,a,b) for(int i(a),_b(b);i<=_b;++i)
#define ford(i,a,b) for(int i(a),_b(b);i>=_b;--i)
#define forn(i,n) fori(i,0,n-1)
#define fora(i,a) forn(i,sz(a))
#define fore(it,c) for(typeof((c).begin()) it=(c).begin();it!=(c).end();++it)
#define all(a) a.begin(),a.end()
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define clear0(a) memset(a,0,sizeof(a))
#define clearm1(a) memset(a,-1,sizeof(a))
#define maximum(a) (*max_element(all(a)))
#define minimum(a) (*min_element(all(a)))
#define findx(a,x) (find(all(a),x)-a.begin())
#define two(X) (1LL<<(X))
#define contain(S,X) ((S)&two(X))
#define setbit(S,X) ((S)|=two(X))
#define clearbit(S,X) ((S)&=~two(X))
#define togglebit(S,X) ((S)^=two(X))
#define sqr(a) ((a)*(a))
#define finp "input.inp"
#define fout "output.out"
#define nmax 41
#define mmax 1601
#define kmax 10
#define modulo 1000000007
#define maxc 999999999

#define debugprint(a) cout << a << ' '
template <typename T>
void debugprintarr(T arr,int x, int y)
{
    fori(i,x,y) debugprint(arr[i]);
    cout << '\n';
}

template <typename T>
void debugprint2darr(T arr, int x1, int y1, int x2, int y2)
{
    fori(i,x1,y1) debugprintarr(arr[i],x2,y2);
}

class FoxAverageSequence {
int f[nmax][mmax][nmax][2];
void dp(int i,int j,int u)
{
	forn(v,nmax)
	{
		int gr1=v>u;
		if (!gr1) f[i][j][u][gr1]+=f[i-1][j-u][v][1];
		f[i][j][u][gr1]%=modulo; 
		f[i][j][u][gr1]+=f[i-1][j-u][v][0];
		f[i][j][u][gr1]%=modulo; 
	}
}
public:
	int theCount(vector <int> seq) {
		f[0][0][0][0]=1;
		int n=sz(seq),kq=0;
		fori(i,1,n)
		forn(j,mmax)
		{
			if (seq[i-1]==-1)
			{
				forn(u,nmax)
				{
					if ((i==1 && j>=u) || (i>1 && u<=(j-u)/(i-1))) dp(i,j,u);
					if (i==n) kq+=(f[i][j][u][0]+f[i][j][u][1])%modulo;
					kq%=modulo;
				}
			} else 
			{
				int u=seq[i-1];
				if ((i==1 && j>=u) || (i>1 && u<=(j-u)/(i-1)))dp(i,j,u);
				if (i==n) kq+=(f[i][j][u][0]+f[i][j][u][1])%modulo;
				kq%=modulo;
			}
		}
		return kq;
	}
};


// BEGIN KAWIGIEDIT TESTING
// Generated by KawigiEdit-pf 2.3.0
#include <iostream>
#include <string>
#include <vector>
#include <ctime>
#include <cmath>
using namespace std;
bool KawigiEdit_RunTest(int testNum, vector <int> p0, bool hasAnswer, int p1) {
	cout << "Test " << testNum << ": [" << "{";
	for (int i = 0; int(p0.size()) > i; ++i) {
		if (i > 0) {
			cout << ",";
		}
		cout << p0[i];
	}
	cout << "}";
	cout << "]" << endl;
	FoxAverageSequence *obj;
	int answer;
	obj = new FoxAverageSequence();
	clock_t startTime = clock();
	answer = obj->theCount(p0);
	clock_t endTime = clock();
	delete obj;
	bool res;
	res = true;
	cout << "Time: " << double(endTime - startTime) / CLOCKS_PER_SEC << " seconds" << endl;
	if (hasAnswer) {
		cout << "Desired answer:" << endl;
		cout << "\t" << p1 << endl;
	}
	cout << "Your answer:" << endl;
	cout << "\t" << answer << endl;
	if (hasAnswer) {
		res = answer == p1;
	}
	if (!res) {
		cout << "DOESN'T MATCH!!!!" << endl;
	} else if (double(endTime - startTime) / CLOCKS_PER_SEC >= 2) {
		cout << "FAIL the timeout" << endl;
		res = false;
	} else if (hasAnswer) {
		cout << "Match :-)" << endl;
	} else {
		cout << "OK, but is it right?" << endl;
	}
	cout << "" << endl;
	return res;
}
int main() {
	bool all_right;
	bool disabled;
	bool tests_disabled;
	all_right = true;
	tests_disabled = false;
	
	vector <int> p0;
	int p1;
	
	{
	// ----- test 0 -----
	disabled = false;
	int t0[] = {3,-1};
			p0.assign(t0, t0 + sizeof(t0) / sizeof(t0[0]));
	p1 = 4;
	all_right = (disabled || KawigiEdit_RunTest(0, p0, true, p1) ) && all_right;
	tests_disabled = tests_disabled || disabled;
	// ------------------
	}
	
	{
	// ----- test 1 -----
	disabled = false;
	int t0[] = {5,3,-1};
			p0.assign(t0, t0 + sizeof(t0) / sizeof(t0[0]));
	p1 = 2;
	all_right = (disabled || KawigiEdit_RunTest(1, p0, true, p1) ) && all_right;
	tests_disabled = tests_disabled || disabled;
	// ------------------
	}
	
	{
	// ----- test 2 -----
	disabled = false;
	int t0[] = {-1,0,40};
			p0.assign(t0, t0 + sizeof(t0) / sizeof(t0[0]));
	p1 = 0;
	all_right = (disabled || KawigiEdit_RunTest(2, p0, true, p1) ) && all_right;
	tests_disabled = tests_disabled || disabled;
	// ------------------
	}
	
	{
	// ----- test 3 -----
	disabled = false;
	int t0[] = {-1,40,-1,-1,-1,10,-1,-1,-1,21,-1};
			p0.assign(t0, t0 + sizeof(t0) / sizeof(t0[0]));
	p1 = 579347890;
	all_right = (disabled || KawigiEdit_RunTest(3, p0, true, p1) ) && all_right;
	tests_disabled = tests_disabled || disabled;
	// ------------------
	}
	
	{
	// ----- test 4 -----
	disabled = false;
	int t0[] = {-1,12,25,0,18,-1};
			p0.assign(t0, t0 + sizeof(t0) / sizeof(t0[0]));
	p1 = 58;
	all_right = (disabled || KawigiEdit_RunTest(4, p0, true, p1) ) && all_right;
	tests_disabled = tests_disabled || disabled;
	// ------------------
	}
	
	if (all_right) {
		if (tests_disabled) {
			cout << "You're a stud (but some test cases were disabled)!" << endl;
		} else {
			cout << "You're a stud (at least on given cases)!" << endl;
		}
	} else {
		cout << "Some of the test cases had errors." << endl;
	}
	return 0;
}
// END KAWIGIEDIT TESTING
